Automatic control system for construction vehicles



J- CURLETT Jan. 10, 1967 AUTOMATIC CONTROL SYSTEM FOR CONSTRUCTIONVEHICLES 5 'SheetsvSheet 1 Original Filed March 20, 1963 INVENTOR.

JOHN CURLETT ATTORNEY J. CURLETT Jan. 10, 1967 AUTOMATIC CONTROL SYSTEMFOR CONSTRUCTION VEHICLES 5 Sheets-Sheet 2 Original Filed March 20, 1963INVENTOR JOHN c'uRLE ATTORNEY Jan. 10, 1967 J. CURLETT 3,296,722

AUTOMATIC CONTROL SYSTEM FOR CONSTRUCTION VEHICLES Original Filed March20, 1963 5 Sheets-Sheet 5 INVENTOR JOHN CURLETT BY W K OM14) ATTORNEYUnited States Patent Ofilice 3,296,722 Patented Jan. 10, 1967 3,296,722AUTOMATIC CONTROL SYSTEM FOR CONSTRUCTION VEHICLES John Curlett, LosGatos, Calif., assignor to Gurries Manufacturing Co., San Jose, Calif.,a corporation of California Continuation of application Ser. No.266,597, Mar. 20, 1963. This application Mar. 29, 1965, Ser. No. 446,468

7 Claims. (Cl. 37-144) This invention relates to an automatic controlsystem for construction vehicles, and more particularly to systems forcontrolling the elevation and cross-slope of working tools for roadbuilding machines and the like, including systems for transferring powerinput from a lift mechanism on one side of the working tool to the liftmechanism on the other side. The present application constitutes acontinuation of applicants co-pending application, Ser. No. 266,597filed March 20, 1963 and now abandoned.

The automatic elevation and cross-slope system of this invention may beemployed in road building and land leveling machinery of a wide varietyof types such as scrapers, grading machines, smoothing and levelingmachines, agricultural machines and the like. In each of these vehiclesthere is a main frame and a working tool which is supported on the frameand hydraulic rams, jack screws or similar extensible members areprovided in order to raise and lower the working tool or the frame onwhich it is supported, in order to adjust the elevation of the tool. Incertain machines of this type, means have been provided for controllingthe elevation of the working tool automatically, as for example in ahydraulic system, a valve may be operated in response to deviation ofthe working tool from a desired reference elevation as determined by aguide wire or reference surface along the path of vehicle travel.

Various devices have also been provided for controlling cross-slope. Incertain of these devices a pendulum is provided to operate a valve, aswitch or any other member capable of controlling the power source whenthe tool inclination deviates from a selected slope.

Efforts have been made to combine automatic controls for both elevationand cross-slope, but such controls usually require considerableadditional power to operate the power lift mechanism on one side of theworking tool in order to supplement or subtract from the power deliveredby the elevation control system. Further, where hydraulic controls areemployed, the amount of oil flow delivered to or taken from thehydraulic ram on one side in order to adjust the slope requires sloweraction of the cross-slope control.

Additionally, the pendulum of such cross-slope control devices isusually place-d directly on the tool that is being controlled. However,the placement of the pendulum on the tool may subject it to impactshocks that could produce inadvertent operation, and it sharplyrestricts the speed with which the tool may be moved. That is, if thetool is tilted at a rate faster than the pendulum can move through itsoil bath, the pendulum will be carried with it to cause anover-correction.

It is, therefore, an object of this invention to provide a system forcontrolling both elevation and cross-slope that operates rapidly andaccurately.

It is a further object of this invention to provide a pendulum-operatedcross-slope control that need not be mounted directly on the tool beingcontrolled.

The automatic control system of this invention comprises an elevationcontrol system which operates power mechanisms by delivering a quantityof power input in response to the output of a sensor device whichcooperates with an external reference surface disposed along the path ofvehicle movement, e.g., a grade wire, a rail or a preformed surface. Forexample, in the case of hydraulic ram tool operating means, the sensorcould operate a valve which is moveable in either direction from anormal, closed position to open the hydraulic system to either pressureor return lines to cause extension or retraction of the hydraulic rams.With the valve open there is delivered into the hydraulic system, thequantity of oil necessary to position the working tool at the desiredelevation at which point the sensor will close the valve. Then,variations in tool inclination may be produced simply by transferringthe pressure fluid from one ram to the other, with little additionalpower requirement. In such a system, a pendulum operated power inputcontrol may be caused to move from a central null position in eitherdirection to drive a motor in a corresponding direction, the motor inturn driving a pump in the appropriate direction to transfer the fluidfrom one hydraulic ram to the other. Thus, one ram will be raised andthe other lowered so that each ram is moved only one-half the amount asingle ram on one side would. Additionally, the only further powerrequirement is that necessary to overcome friction and the relativelysmall difference in load between rams.

As an additional feature of this invention, the pendulum control may bemounted on the vehicle frame rather than on the tool and the power inputcontrol is operated disjunctively by the pendulum and by a feedbackincrement transmitted from the tool in response to slope movement. Thus,movement to the correct tool slope will overcome pendulum operationdespite continued frame slope error.

Other objects and advantages of this invention will become apparent fromthe specification following when read in conjunction with theaccompanying drawings wherein:

FIG. 1 is a view in perspective of a road building vehicle incorporatingthe automatic control system of this invention;

FIG. 2 is a schematic diagram of a preferred form of hydraulic controlsystem;

FIG. 3 is a schematic illustration of an alternative fluid controlsystem; and

FIG. 4 is a schematic diagram of an alternative mechanical controlsystem.

Referring now to the drawings, and particularly to FIG. 1 thereof, thereis shown a construction machine 10 comprising a main frame 12 mountedupon suitable traction means such as the wheels 14 illustrated. Thecontrol system of this invention is applicable to control a wide varietyof working tools, but in the illustration shown there is provided aleveling and smoothing device 16 carried on the end of arms 18 which arepivotally mounted to swing about pivot points 20. The position of theleveling device 16 bears a fixed relation to the position of the pivotpoints 20 so that control of the pivot points 20 will inherently producecontrol of the leveling device. In the machine shown, the pivot points20 are carried on the lower end of the piston rods 22 of the hydraulicrams 24 secured at 26 to the main frame 12 so that extension andretraction of the hydraulic, rams will result in a raising and loweringof the pivot points 20. As the pivot points 20 are changed, theangular'disposition of the arms 18 and leveling device 16 are variedtemporarily, but the latter readjusts itself automatically to establisha new leveling plane at a lower or higher level, as the case may be.Such action is well known in the art, in and of itself, forms no part ofthe present invention. An exemplary arrangement of this type isdescribed in US. Patent No. 3,029,715 to which reference is made fordetails of its structure and operation.

The pivot points 20 may be raised and lowered automatically by operationof a control valve 28 (FIG. 2), such as a four-way valve of conventionalnature and corresponding to valve 70 in FIG. 2, such valve beingmoveable in either direction from a central neutral position to directthe flow of hydraulic fluids in the lines as indicated by arrows in FIG.2 to extend or retract the hydraulic rams 24. For example, when it isdesired to lower the working tool 16 the four-way valve 28 may beoperated to open the upper ends of the hydraulic rams 24 to pressurefluid P and the lower ends to the return lines R so that the rams 24will be driven down to carry the pivot points 20 with it. In conjunctionwith this system, a suitable flow divider 29 such as that described inPatent No. 3,000,122 is provided to insure to insure that fluid flow toand from both of the cylinders is uniform so that each ram 24 will beextended or retracted in equal amounts.

The four-way valve 28 may be operated by means of a sensor devicecomprising an arm 30 pivotally carried on the valve body directly tooperate the four-way valve, the arm preferably being counter-weighted at32 so that it normally maintains desired neutral position balance, thearrangement being substantially as described in copending patentapplication, Ser. No. 198,392, now United States Patent No. 3,142,915.The outer end of the arm may be bifurcated at 34 to ride over a gradewire 36 (FIG. 1) carried on suitable posts 38 so that as the vehiclemoves along the path of travel the valve will be maintained in itsneutral closed position as long as the arm 30 is at the desired heightwith respect to the grade wire 36. Since the arm 30 is mounted to movewith the pivot mountings 20, the deviation of the arm from the desiredheight indicates corresponding deviation of the working tool. Theinitial position of the sensor device can be established by means of acrank 40 which may be turned manually to adjust the height of the valve28 and sensor device 30 relative to plates 42 on the arms 18 to assume aneutral position at the desired height of the tool being controlled.

The cross-slope assembly may be contained in a housing 44 mounted on themain frame 12 and preferably includes a pendulum-controlled source ofpower like that disclosed in detail in Patent No. 2,934,078 whichoperates the hydraulic rams 24 in response to deviation of the framefrom a desired cross-slope to correct the slope. Working in oppositionto the cross-slope control 44 is a feed-back transmitting shaft 46 whichdelivers motion produced by the correcting movement of the working tool,or pivot points in this case, to inactivate the power source whencorrection is achieved. The feed-back trans mitting shaft 46 may includesuitable universal members 48 and operates to transmit rotationdelivered from a differential gear arrangement 50 connected between twofeed-back input shafts 52, 54 which are driven in opposite directions byunidirectional movement of the opposite ends of the controlled workingtool. Thus, if both sides of the working tool are raised equal amountsthe shafts 52 and 54 will rotate in opposite directions equal amountsand there will be no output at the differential gear 50 to the shaft 46.By the same token, any difference in the amount of movement between theopposite sides of the working tool will result in an output at thedifferential gear which is transmitted through the shaft 46 to thecrossslope control.

The feed-back system may take a variety of forms but preferablycomprises chains 56 and 57 secured at their lower ends to the plates 42on the arms 18 and trained in opposite directions about sprockets 58 and59 on the feed back shafts 52 and 54 to drive the sprockets in oppositedirections. A spring or other suitable tension means shown generally at60 and 62 on the main frame 12 bias the chains in full tension away fromthe working tool.

Thus, a pendulum in the housing 44 will detect a deviation in slope ofthe frame 12 from a desired reference and, as will be described, a powersource is actuated to operate the hydraulic rams in directions tocorrect the slope of the working tool measured from the mountings 20.The correcting movement of opposite sides of the working tool willnecessarily be differential resulting in an increment of rotation beingtransmitted by the feed-back delivery shaft 46 in opposition to theoperation of the pendulum until, when correction is complete, the powersource is inactivated.

A manually operated drive mechanism 64 is provided for controlling thepower source so that the initial setting may 'be chosen from theoperators seat. The manual control 64 may comprise simply a chain andsprocket drive connected through a differential 66 to the feed-backdelivery shaft 46 to control operation of the power source in adirection opposite to that of the pendulum control as will be described.

Referring now to FIG. 2, the power controlling member may comprise afour-way valve 70, including a spool 71 that is moveable in eitherdirection from the neutral position shown to open the fluid lines 73 ofa hydraulic motor system selectively to the pressure or return lines 72and 74 of a constant pressure hydraulic system. It is to be noted thatthe spool 71 may be contoured so that the forces of fluids moving inopposite directions are balanced. This is a particular advantage ofsystems using a four-way valve open selectively to bi-directional flow.

When the valve is moved a given direction, the hydraulic motor 76 willbe caused to be driven in a corresponding direction so that a hydraulicpump 78 connected to the motor by suitable coupling 80 will circulatethe fluid in the hydraulic ram system from one hydraulic ram 24 to theother.

The amount of hydraulic fluid originally delivered to the system isdetermined by the side tracer servo valve 28 which is open from aneutral closed position by operation of the sensor arm 30 as previouslydescribed. A- pair of manually operated selector valves 82, 83 areprovided so that either one or the other of the side tracer servos 28 or28a may be activated. Assuming that the servo tracer on the left is theactivated one, as shown, operation of that valve 28 will permit fluid toflow according to the align ment of the pressure and return lines untilthe desired elevation of the hydraulic rams 24, and hence the workingtool, is achieved with the flow of fiuid being through the flow divider29 so that hydraulic rams are operated equally. Then, with the fluidthus introduced into the system operation of the hydraulic pump 78merely transfers the fiuid from one hydraulic ram 24 to the otherwithout increasing the pressure substantially. Since the slope of theworking tool is varied by extending one hydraulic ram 24 while the otheris retracted the stroke of each is only one-half of that required bycorrecting through only one of the cylinders. It is to be noted alsothat while double acting rams are shown in FIG. 2 the fluid transfersystem here described is equally applicable to single acting cylinders.

One system for operating the four-way valve 70 is illustrated in FIG. 2and comprises a difierential lever 86 pivotally connected at one end bymeans of a link 88 to an arm 89 carried on a pendulum 90 suspended froma fixed pivot 91 so that oscillation of the pendulum indicating a changein slope will raise or lower one end of the differential lever to raiseor lower the spool 71, connected to the center of the lever, from itsneutral, closed position. The other end of the differential lever 86 ispivotally connected by means of a link 92 to a bell crank lever 94 whichis pivoted about a fixed point 95 in response to input from thefeed-back control. One means of accomplishing this would be to provide agear segment 96 on the bell crank lever 94 as shown and drive the bellcrank lever by means of a pinion 98 carried on the input shaft to whichthe manual drive mechanism 64 and feedback shaft 46 are connected bymeans of the differential gears 66. The system is arranged so thatfeed-back input will work in the direction opposite to that of thependulum control, and corrective movements of the working tool willnullify the output of the pendulum which actually reflects deviationslope of the frame 12 rather than the working tool 16, 18.

In the system shown in FIG. 3, operation of the side tracer servo 102produces bi-directional fluid flow as in FIG. 2 so that the flow isdivided by operation of a pair of fluid pump motors 104, 106 carried onshafts between which is interposed a gear differential 108. Thus, withthe differential inactive the fluid drives the motors at equal ratesand, in turn, the pump motors 104, 106 deliver fluid in equal quantitiesto extend or retract the hydraulic rams 110 in equal amounts. Inconjunction with this system there is provided a four-way pendulum servo112 similar to that shown in FIG. 2 which operates in response todeviations from a desired slope to cause fluid flow in the desireddirection to drive a fluid motor 114 in a corresponding direction. Thefluid motor will deliver an input to the gear differential 108 toincrease the rotation of one fluid pump and decrease the rotation of theother, thus producing greater flow of fluid to one hydraulic ram andreducing the flow to the other. If the fluid pumps are initially idleafter the rams are in positions established by the elevation control,operation of the transfer fluid member 114, 108 will merely produce flowfrom one hydraulic ram to the other.

In FIG. 4, there is shown a mechanical drive for accomplishingcross-slope control. There, a pair of jack screws 120 which are securedto the working tool pivot points 20 are engaged by nuts 122 on which areformed bevel gears 124 driven by suitable pinions 126 carried on theends of a shaft 128. On the shaft is secured a gear 130 driven by amotor 132 through a second gear 134 and adapted to be operated from theblade height sensor unit 102. Thus, the sensor unit could be moved froma neutral position to close a switch in either direction and drive themotor in corresponding direction. Similarly, a pendulum sensing unit maycontrol a current to a transfer motor 136 which operates a split-pathbevel gear 138 to produce rotation of shafts in opposite directions.Then, suitable differential gears 140 are provided to introduce relativerotation of the shafts in opposite directions to add to or subtract fromthe movement produced by the elevation control,

While this invention has been described in conjunction with preferredembodiments thereof, it is to be under stood that modifications andchanges therein may be made by those skilled in the art within thespirit and scope of this invention which is to be defined by the claimsappended hereto.

What is claimed is:

1. A control system for a construction vehicle having a working toolframe adapted for vertical adjustment relative to the vehicle framewhich system comprises means including a pair of extensible membersconnected between the vehicle frame and the working tool frame atlaterally spaced portions thereof for individually adjusting therespective sides of the Working tool frame, a first sensing meansoperative to energize aid extensible members simultaneously in the samedirection to vary the elevation of the working tool frame, and a secondsensing means operative to automatically energize said extensiblemembers simultaneously in opposite directions to vary the cross-slope ofthe working tool frame.

2. A control system according to claim 1 in which said first sensingmeans for controlling said elevation-varying means includes a sensingmember supported from the working tool frame and adapted to engage areference surface disposed along the path of vehicle travel.

3. A control system according to claim 1 in which said second sensingmeans for controlling said cross-slope varying means includes a pendulumsuspended from the vehicle frame, and feed-back means connected betweenthe working tool frame and said control means to inactivate the latterwhen the working tool frame has attained a predetermined cross-slopedisposition.

4. A control system according to claim 1 wherein said extensible membersare jack screws.

5. A control system according to claim 1 wherein said extensible membersare hydraulic rams and said elevation varying means includes a hydraulicpressure system arranged to deliver equal amounts of hydraulic fluid tosaid rams,

6. A control system according to claim 5 wherein said cross-slopevarying means includes a pump connected to transfer hydraulic fluid fromone of said rams to the other.

7. A control system for a construction vehicle having a working toolframe adapted for adjustment relative to the vehicle frame which systemcomprises means including a pair of extensible members connected betweenthe frame and the working tool frame at laterally-spaced por tionsthereof for individually adjusting the respective sides of the workingtool frame, sensing means operative to automatically energize saidextensible members in opposite directions to vary the cross-slope of theworking tool frame, means for controlling said cross-slope varying meansincluding a pendulum suspended from the vehicle frame, and feed-backmeans connected between the working tool frame and said control means toinactivate the latter when the working tool has attained a predeterminedcross-slope disposition, said feed-back means including a pair offeed-back shafts connected to the sides of the Working tool frame so asto rotate in opposite directions in response to adjustment of theworking tool frame, a differential gear unit connected to said shafts,and a control input shaft connected between said differential gear unitand said control means whereby said I control shaft rotates only inresponse to variation in the cross-slope of the working tool frame.

References Cited by the Examiner UNITED STATES PATENTS 2,190,346 2/1940Austin 37 2,310,930 2/1943 Blanchett 280-61 2,524,005 10/ 1950 Hurbert172-465 X 2,636,290 4/1953 Bell 37 2,756,062 7/1956 Thixton 280-612,775,831 1/1957 Rockwell 37144 2,934,078 4/1960 Gurries et .al 37-180 X3,008,724 11/1961 Lapins et a1 2806.1 3,094,796 6/1963 Atchley 37156ABRAHAM G. STONE, Primary Examiner.

JOE O. BOLT, WILLIAM A. SMITH III, Examiners.

1. A CONTROL SYSTEM FOR A CONSTRUCTION VEHICLE HAVING A WORKING TOOLFRAME ADAPTED FOR VERTICAL ADJUSTMENT RELATIVE TO THE VEHICLE FRAMEWHICH SYSTEM COMPRISES MEANS INCLUDING A PAIR OF EXTENSIBLE MEMBERSCONNECTED BETWEEN THE VEHICLE FRAME AND THE WORKING TOOL FRAME ATLATERALLY SPACED PORTIONS THEREOF FOR INDIVIDUALLY ADJUSTING THERESPECTIVE SIDES OF THE WORKING TOOL FRAME, A FIRST SENSING MEANSOPERATIVE TO ENERGIZE SAID EXTENSIBLE MEMBERS SIMULTANEOUSLY IN THE SAMEDIRECTION TO VARY THE ELEVATION OF THE WORKING TOOL FRAME, AND A SECONDSENSING MEANS OPERATIVE TO AUTOMATICALLY ENERGIZE SAID EXTENSIBLEMEMBERS SIMULTANEOUSLY IN OPPOSITE DIRECTIONS TO VARY THE CROSS-SLOPE OFTHE WORKING TOOL FRAME.